U.S. patent application number 11/236128 was filed with the patent office on 2006-09-07 for solid regenerated standard viscose fibres.
Invention is credited to Daniel Thomas Blair, Christoph Boxan, Heinrich Schmidt, Josef Schmidtbauer.
Application Number | 20060200103 11/236128 |
Document ID | / |
Family ID | 33034705 |
Filed Date | 2006-09-07 |
United States Patent
Application |
20060200103 |
Kind Code |
A1 |
Schmidtbauer; Josef ; et
al. |
September 7, 2006 |
Solid regenerated standard viscose fibres
Abstract
The present invention relates to a solid regenerated standard
viscose fibre. The fibre according to the invention has a cross
section the area of which is larger than the area of the largest
equilateral triangle inscribed into said cross section by a factor
of less than 2.50 times, preferably less than 2.40 times,
especially preferred less than 2.25 times. Furthermore, the fibre
according to the invention has a Syngina absorbency as defined
hereinbefore of more than 6.0 g/g fibre.
Inventors: |
Schmidtbauer; Josef;
(Vocklabruck, AT) ; Schmidt; Heinrich;
(Vocklabruck, AT) ; Boxan; Christoph; (Lenzing,
AT) ; Blair; Daniel Thomas; (Morristown, TN) |
Correspondence
Address: |
BAKER & BOTTS
30 ROCKEFELLER PLAZA
44TH FLOOR
NEW YORK
NY
10112
US
|
Family ID: |
33034705 |
Appl. No.: |
11/236128 |
Filed: |
September 27, 2005 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
PCT/AT04/00074 |
Mar 8, 2004 |
|
|
|
11236128 |
Sep 27, 2005 |
|
|
|
Current U.S.
Class: |
604/358 |
Current CPC
Class: |
A61L 15/28 20130101;
D01D 5/253 20130101; D01F 2/08 20130101; A61L 15/28 20130101; C08L
1/24 20130101; D01F 2/06 20130101 |
Class at
Publication: |
604/358 |
International
Class: |
A61F 13/15 20060101
A61F013/15 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 27, 2003 |
AT |
A 488/2003 |
Claims
1. A solid regenerated standard viscose fibre having a cross
section the area of which is larger than the area of the largest
equilateral triangle inscribed into said cross section by a factor
of less than 2.50 times, and having a Syngina absorbency as defined
hereinbefore of more than 6.0 g/g fibre.
2. A fibre according to claim 1, in the form of staple fibre.
3. A fibre according to claim 1 or 2, having a titre of from 0.5
dtex to 6.0 dtex.
4. A fibre according to claim 1 or 2, having a water retention
value measured according to DIN 53814 of from 70 to 110%.
5. A process for the manufacture of a solid regenerated standard
viscose fibre, comprising: spinning a standard viscose spinning
dope through a spinneret comprising spinning holes into a
regenerating bath thereby forming filaments, wherein (i) said
spinning holes comprise a multi-limbed orifice the limbs of said
orifice having an aspect ratio of lower than 3:1; (ii) said viscose
spinning dope has a ripening index of 10-20.degree. Hottenroth, and
(iii) said viscose spinning dope contains 0.1-7 wt. %, based on
cellulose of a viscose modifier; (iv) said regenerating bath
contains from 70 to 100 g/l sulfuric acid, from 240 to 380 g/l
sodium sulphate, and from 5 to 30 g/l zinc sulphate; and (v) said
regenerating bath has a temperature of from 25 to 55.degree. C.,
and (b) stretching and further treating said filaments.
6. A process according to claim 5, wherein the viscose modifier is
a polyethylene glycol with a molecular weight of 600-3000.
7. A process according to claim 5 or 6, wherein said filaments are
treated with a fatty acid ester.
8. A process according to claim 5 or 6, wherein said filaments are
treated with a polyoxyethylene sorbitan fatty acid ester.
9. An absorbent product, comprising a fibre according to claim
2.
10. A solid regenerated standard viscose fibre according to claim 1
or 2 wherein said factor by which the area of the cross section is
larger than the area of the largest equilateral triangle inscribed
into said cross section is less than 2.40 times.
11. A solid regenerated standard viscose fibre according to claim 1
or 2 wherein said factor by which the area of the cross section is
larger than the area of the largest equilateral triangle inscribed
into said cross section is less than 2.25 times.
12. An absorbent product, comprising a fibre according to claim 2
having a titre of from 0.5 dtex to 6.0 dtex.
13. A tampon, comprising a fibre according to claim 2 having a
titre of from 0.5 dtex to 6.0 dtex.
14. An absorbent product, comprising a fibre according to claim 2
having a water retention value measured according to DIN 53814 of
from 70 to 110%.
15. A tampon, comprising a fibre according to claim 2 having a
water retention value measured according to DIN 53814 of from 70 to
110%.
16. A process for the manufacture of a solid regenerated standard
viscose fibre, comprising: (a) spinning a standard viscose spinning
dope through a spinneret comprising spinning holes into a
regenerating bath thereby forming filaments, wherein (i) said
spinning holes comprise a multi-limbed orifice, the limbs of said
orifice having an aspect ratio of about 3:1 or less; (ii) the
viscose spinning dope has a ripening index of 10-20.degree.
Hottenroth; (iii) the viscose spinning dope contains 0.1-7 wt. %
based on cellulose of a viscose modifier; and (iv) the regenerating
bath contains from 75 to 85 g/l sulfuric acid, from 270 to 300 g/l
sodium sulphate, and from 7 to 12 g/l zinc sulphate; and (v) the
regenerating bath has a temperature of from 25 to 55.degree. C.;
and (b) stretching and further treating said filaments.
17. A process for the manufacture of a solid regenerated standard
viscose fibre, comprising: (a) spinning a standard viscose spinning
dope through a spinneret comprising spinning holes into a
regenerating bath thereby forming filaments, wherein (i) said
spinning holes having a three-limbed orifice, the limbs of said
orifice having an aspect ratio of about 3:1 or less, (ii) the
viscose spinning dope has a ripening index of 12-16.degree.
Hottenroth, and (iii) contains 2-6 wt. % based on cellulose, of a
viscose modifier (iv) the regenerating bath contains from 75 to 85
g/l sulfuric acid, from 270 to 300 g/l sodium sulphate, and from 7
to 12 g/l zinc sulphate; and (iv) the regenerating bath having a
temperature of from 30 to 35.degree. C., (b) stretching and further
treating said filaments.
18. A process according to claim 16 or 17, wherein the viscose
modifier is a polyethylene glycol with a molecular weight of
600-3000.
19. A process according to claim 16 or 17, wherein said filaments
are treated with a fatty acid ester.
20. A process according to claim 16 or 17 wherein said filaments
are treated with a polyoxyethylene sorbitan fatty acid ester.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of International Patent
Application No. PCT/AT2004/000074 filed Mar. 8, 2004, designating
the United States and published in the German language on Oct. 7,
2004 under International Patent Publication No. WO 2004/085720,
which is based on Austrian Patent Application No. A 488/2003 filed
Mar. 27, 2003, to each of which priority is claimed, and each of
which is incorporated by reference in its entirety herein.
FEDERALLY FUNDED GRANT SUPPORT
[0002] Not applicable.
1. INTRODUCTION
[0003] The present invention relates to a solid regenerated
standard viscose fibre and a process for the manufacture of said
fibre.
2. BACKGROUND OF THE INVENTION
[0004] State-of-the-art fibre materials commonly used for the
manufacturing of tampons are regular viscose fibres, so-called
trilobal viscose fibres and cotton. The specific absorbency of
these fibres according to the Syngina Test as described below is
approximately 4.5 g/g for cotton, 5.5 g/g for regular viscose and
6.5 g/g for trilobal viscose fibres.
[0005] It is the aim of tampon manufacturers to obtain a certain
level of absorbency with a minimum amount of fibre material and
costs.
[0006] Whereas cotton is going to be phased out as a fibre material
for tampons due to its insufficient absorbency, trilobal fibres are
much more expensive to produce and much more difficult to process
into tampons compared to regular viscose.
[0007] In order to enhance the absorbency of cellulosic fibres,
many different approaches have been reported: [0008] 1. a chemical
modification by grafting of monomers onto the cellulosic fibre,
[0009] 2. a chemical modification by incorporation of absorbent
polymers like carboxymethyl-cellulose, chitosan, cellulose
carbamate, alginate or guaran into the cellulosic fibre matrix
[0010] 3. a physical modification of the fibres such as hollow
fibres or collapsed hollow fibres as known for example from U.S.
Pat. No. 4,129,679 or [0011] 4. multilimbed fibres (so-called
"trilobal" fibres) obtained by using spinnerets with multilimbed
extrusion holes having at least 3 limbs with an aspect ratio of 2:1
to 10:1 as known for example from EP-A1 0 301 874.
[0012] The disadvantage of a chemical modification of the
cellulosic fibre is, that a costly and time-consuming toxicological
and physiological testing procedure is needed for very sensitive
medical applications like tampons and that the occurrence of the
Toxic Shock Syndrom (TSS) prevents most tampon manufacturers from
using chemically modified fibre materials, although the chemicals
may regarded as safe.
[0013] The disadvantage of hollow and collapsed hollow fibres is,
that they are difficult to produce because of their high water
retention value, which makes the fibres swell strongly during
washing and stick together by formation of hydrogen bonds during
drying, making them brittle in the dry state, soapy in the wet
state and difficult to open and process into a carded web.
[0014] The use of trilobal fibres has continuously increased during
the past couple of years, although trilobal fibres are much more
difficult to process into a tampon. The small limbs of the fibres
are very fragile and may easily be damaged by mechanical forces
which are applied during processing of the fibres, especially
during carding under formation of fibre dust.
[0015] The manufacture of multi-limbed viscose fibres has been
described e.g. in U.S. Pat. Nos. 5,634,914 and 5,458,835 and EP-A1
0 301 874. The process disclosed therein describes the spinning of
a commonly used viscose, which may contain a certain amount of a
modifier known in the art through extrusion holes having a
multi-limbed shape, especially a trilobal shape into a conventional
spinbath. The essential feature of this process is that the shape
of the multi-limbed extrusion holes in the spinneret is similar to
the desired shape of the cross section of the filaments. According
to the teaching of these documents, the geometry of the spinneret
hole determines the shape of the fibre cross section and a certain
aspect ratio of the fibre cross section can be obtained by a
corresponding design of the extrusion holes.
[0016] The state of the art in regard to multi-limbed fibres,
furthermore, teaches that such multi-limbed fibres have an
increased absorbency compared to state-of-the-art viscose fibres,
especially in tampons and that such fibres need to have at least 3
limbs and that each limb of such fibres needs to have an aspect
ratio of at least 2:1, most preferably of 3:1 to 5:1. The higher
the aspect ratio, the higher would be the degree of free volume and
the absorbency of the fibres, provided that the limbs are not so
long and thin that they bend back upon themselves.
[0017] As described in e.g., U.S. Pat. Nos. 5,634,914 and
5,458,835, the aspect ratio is the ratio of the length to the
average width of the fibre limbs. This ratio may be calculated for
each limb by taking one length measurement and three width
measurements. The widths are measured at about the midpoint and at
either end of the limb and then the average width of the limb is
calculated from the three measurements.
[0018] It is also mentioned in these documents without further
evidence, that even higher absorbencies of multilimbed fibres can
be achieved under slow regeneration spinning conditions, e.g. by
decreasing the acid level and/or increasing the sulphate level
and/or addition of a viscose modifier.
[0019] The fact that concavities in the cross section of viscose
fibres enhances the absorbency of these fibres and the products
made therefrom is, furthermore, known from U.S. Pat. No. 4,362,159.
In addition, U.S. Pat. No. 4,129,679 discloses that a multi-limbed
cross section of the viscose fibres confers greater absorbency from
the products made from the filaments by virtue of the capacity of
the filament bundle to hold large quantities of interstitial water
between adjacent limbs of filaments.
3. SUMMARY OF THE INVENTION
[0020] It has now surprisingly been found that it is possible to
produce a viscose fibre from spinnerets with multi-limbed orifices,
whereby the cross section of the fibre is of a substantially
triangular shape not having limbs with an aspect ratio of less than
2:1. This fibre avoids the drawbacks of multi-limbed fibres, but
surprisingly although not having a multi-limbed cross section, the
fibre is highly absorbent.
[0021] Accordingly, the present invention relates to a solid
regenerated standard viscose fibre having a cross section the area
of which is larger than the area of the largest equilateral
triangle inscribed into said cross section by a factor of less than
2.50 times, preferably less than 2.40 times, especially preferred
less than 2.25 times, and having a Syngina absorbency as defined
hereinafter of more than 6.0 g/g fibre.
4. BRIEF DESCRIPTION OF THE FIGURES
[0022] FIG. 1 shows a triangle inscribed into the cross section of
a triangular fibre according to the present invention.
[0023] FIG. 2 shows a triangle inscribed into the cross section of
a trilobal fibre according to the state of the art.
[0024] FIG. 3 depicts the apparatus used to perform the Syngina
test method.
[0025] FIG. 4 depicts the mechanical press used to prepare the test
specimen for the Syngina test method.
[0026] FIG. 5 is a sectional view of a component of the mechanical
press of FIG. 4, according to lines A-A.
[0027] FIG. 6 is a sectional view of another component of the
mechanical press of FIG. 4, according to lines B-B.
[0028] FIG. 7 is an enlarged sectional view of region Y in FIG.
5.
[0029] FIG. 8 is an enlarged sectional view of region Z in FIG.
6.
[0030] FIG. 9 to 15 show the shapes of the fibres produced
according to Examples 1 to 7 in enlarged view.
5. DETAILED DESCRIPTION OF THE INVENTION
[0031] For the purposes of the present invention, the term "solid"
shall mean that the fibre has a solid, not hollow or collapsed
structure.
[0032] The term "standard" shall mean that the fibre is a
regenerated cellulosic fibre obtained by the viscose process having
a breaking force in the conditioned state Bc [cN] of less than 1.3
{square root over (T)}+2T and a force required to produce an
elongation of 5% in the wet state Bm [cN] of less than 0.5 {square
root over (T)} where T is the mean linear density in dtex.
[0033] The cross section of the fibre according to the invention
roughly resembles a triangular shape. This triangular shape can be
best defined by comparing the area of the fibre cross section with
area of the largest equilateral triangle inscribed into said cross
section.
[0034] The smaller the difference between the area of the cross
section of the fibre and the area of this largest inscribed
triangle, the more resembles the cross section of the fibre a
triangular shape.
[0035] As can be seen from FIG. 1, in the case of a roughly
triangular shape of the cross section, the area of the cross
section of the fibre is not much larger than the area of the
largest equilateral triangle inscribed into said cross section.
[0036] However, according to FIG. 2, if a triangle is inscribed
into a fibre with a trilobal cross section having limbs with an
aspect ratio of greater than 2:1, the area of the cross section of
the fibre is much larger than the area of the inscribed
triangle.
[0037] According to the present invention, the ratio between the
area of the cross section of the fibre and the area of the largest
inscribed equilateral triangle should be less than a factor of 2.50
times, preferably less than 2.40, especially preferred less than
2.25, said area of the cross section and said factor being
determined according to the methods set out in detail below. For
the purposes of the present invention this factor shall be called
"Delta ratio".
[0038] The article "Verzug, Verstreckung und
Querschnittsmodifizierung" by Dr. Erich Treiber, Chemiefasem
5/1967, 344-348 discloses high wet modulus (HWM) filaments having
been produced with a trilobal spinneret. The titre of the filament
was 3.3 den, the tenacity 4 g/den in conditioned state and 2.4
g/den in wet state and the elongation was 10% resp. 14%. The cross
section of this filament is depicted in FIG. 8a) of this
publication and represents a Delta ratio of 1.67.
[0039] The Treiber publication is silent about the absorbent
properties of such filaments. In general the skilled artisan would
expect, that the water retention value of HWM fibres is
significantly lower than that of viscose fibres.
[0040] The fibre according to the invention is preferably present
in the form of staple fibre.
[0041] The titre of the fibre may be in the range of from 0.5 dtex
to 6.0 dtex, preferably of from 2.5 dtex to 4 dtex.
[0042] Although the fibre according to the invention is a solid
fibre and does not have limbs with an aspect ratio of more than 2:1
as disclosed in EP-A1 0 301 874, the fibre shows superior
absorbency properties: [0043] a specific Syngina absorbency of more
than 6.0 g/g according to the test method disclosed below [0044] a
water retention value measured according to DIN 53814, using the Wt
calculation scheme, of from 70 to 110%, preferably of from 80 to
90%.
[0045] The fibre according to the invention, furthermore, is less
fragile than trilobal fibres due to its characteristic cross
section and exhibits excellent processability during carding.
[0046] The fibre according to the invention is perfectly suitable
for absorbent products, such as a tampon. Therefore, the present
invention also provides an absorbent product, such as a tampon,
including the fibre according to the invention in staple form.
[0047] It has been found that the fibre according to the invention
can be produced with a process comprising the steps of [0048]
spinning a standard viscose spinning dope through a spinneret
comprising spinning holes into a regenerating bath thereby forming
filaments, [0049] said spinning holes having a multi-limbed
orifice, preferably a three-limbed orifice [0050] the limbs of said
orifice having an aspect ratio of lower than 3:1 [0051] said
viscose spinning dope having a ripening index of 10-20.degree.
Hottenroth, preferably 12-16.degree. Hottenroth, and [0052] said
viscose spinning dope containing 0.1-7 wt. %, preferably 2-6 wt. %
based on cellulose of a cellulose modifier [0053] said regenerating
bath containing [0054] from 70 to 100 g/l, preferably 75 to 85 g/l
sulfuric acid, [0055] from 240 to 380 g/l, preferably 270 to 300
g/l sodium sulphate, [0056] from 5 to 30 g/l, preferably 7 to 12
g/l zinc sulphate and [0057] said regenerating bath having a
temperature of from 25 to 55.degree. C., preferably 30 to
35.degree. C., [0058] stretching and further treating said
filaments according to known methods.
[0059] For the purposes of the present invention a standard viscose
spinning dope is a state-of-the-art viscose solution, which is used
to produce standard viscose fibres, typically characterised by a
cellulose concentration of more than 7 wt. %, preferably more than
8%, an alkali ratio of less than 0.9, typically around 0.6, a gamma
value below 50 and a ripening index of 20.degree. Hottenroth and
below.
[0060] Preferably the viscose modifier is a polyethylene glycol
with a molecular weight of 600-3000, preferably 1200-1500.
[0061] All values given in wt. % in the present specification are
calculated on the basis of the weight of cellulose.
[0062] In a preferred embodiment of the process, the filaments are
treated with a fatty acid ester. Preferably the fatty acid ester
used to treat the filaments is a polyoxyethylene sorbitan fatty
acid ester such as TWEEN.RTM.20 (available from ICI
Surfactants).
[0063] The filaments may be treated with the fatty acid ester in an
amount of from 0.03 to 0.7% (w/w calculated on basis of cellulose),
preferably of from 0.3 to 0.4%.
[0064] The stretching and further treatment of the filaments (such
as cutting, finishing and drying) can be accomplished by methods
known as such to the skilled artisan. Typically, the filaments are
stretched after leaving said regenerating bath in a secondary bath
and/or in air at a stretching ratio of from 40% to 90%, preferably
55% to 70%.
[0065] In the state-of-the-art process for the manufacturing of
trilobal fibres, as disclosed e.g. in the experimental part of
EP-AI 0301 874, regeneration conditions are applied which provide a
rapid fixation of the fibre cross section in the same shape as
extruded from the trilobal spinneret hole.
[0066] In the process according to the present invention however it
is of critical importance, that the process parameters are balanced
in that way, that the filaments extruded from a trilobal spinneret
are regenerated slowly by allowing the filaments to contract the
limbs towards the core, thus forming a substantially triangular
cross section (referred to in the following as
".DELTA.-shaped").
[0067] For a certain viscose composition a slow regeneration
process can e.g. be accomplished by dosage of a viscose modifier
into the spinning dope in combination with a reduction of the
sulfuric acid concentration and a low temperature of the
spinbath.
[0068] It can be demonstrated, that in order to obtain
.DELTA.-shaped fibres instead of Y-shaped fibres when spinning
through spinnerets with trilobal orifices, especially the
combination of a modifier and a slow regenerating spinbath appears
to be essential.
[0069] Without addition of a modifier, the cross section of the
fibres obtained from a trilobal spinneret will be Y-shaped, even if
the sulfuric acid concentration and temperature of the spinbath are
reduced.
[0070] However, if a certain amount of modifier, e.g. PEG 1500, is
added to the viscose spinning dope, the cross section of the fibres
spun under the same conditions will be a .DELTA.-shaped cross
section.
[0071] On the other hand, if a conventional spinbath with higher
sulfuric acid concentration is applied, the resulting fibres will
have a Y-shaped cross section irrespective of whether a modifier is
used or not used.
[0072] By using spinnerets the orifices of which have three limbs
with a rather low aspect ratio, such as only slightly above 2:1 or
below 2:1, it is possible to produce .DELTA.-shaped fibres even if
a spinbath with higher sulfuric acid concentration is applied.
[0073] Alternatively, the fibres according to the present invention
can be produced by using spinnerets with triangular holes instead
of trilobal spinnerets. In this case the regeneration conditions
have to be adjusted in a way suitable to preserve the triangular
cross section of the fibre. It has been found that spinning of a
standard viscose spinning dope with an alkali ratio of 0.6 by means
of a spinneret with equilateral triangular holes into a
conventional spinbath or a slow regenerating spinbath with or
without addition of polyethylene glycol as a modifier does not lead
to fibres with a Delta ratio below 2.50 and a Syngina absorbency of
more than 6 g/g fibre. However, if a viscose of high alkali ratio
is spun by means of a triangular spinneret into a spinbath
containing a high concentration of zinc sulphate, .DELTA.-shaped
fibres according to the present invention can be obtained.
[0074] Surprisingly it was found, that fibres with a triangular
cross section as defined above show a significantly better Syngina
absorbency than regular viscose fibres, up to the same level or
even better than trilobal viscose fibres although their cross
section does not comprise limbs with an aspect ratio of more than
2:1. The fibre according to the invention, furthermore, offers
significant advantages in carding and tampon manufacturing due to
its compact shape.
Test Methods
Taking of Photomicrograph of Fibre Cross Section
[0075] A bundle of parallelised staple fibres is threaded through a
hole with a diameter of 1-2 mm in a stainless steel plate. The
protruding fibres are cut off by means of a razor blade parallel to
the surface of the steel plate. The plate is put under a microscope
and a microphotograph of the fibre cross section is taken at a
magnification of 1070:1.
Determination of Largest Inscribed Equilateral Triangle and
Determination of Factor Between Area of Cross Section of the Fibre
and Area of the Largest Inscribed Triangle
[0076] This determination can be performed on a personal computer
via graphical software known as such and custom-made calculation
software as described below. [0077] 1) The profile of a single
fibre is transferred into a bitmap with color values identifying
the fibre against the background. Only such fibre profiles are
selected for graphical evaluation, which are completely visible and
can be easily isolated from the neighbouring profiles, and which
have a high contrast against the background. The fibre cross
section is covered with a coarse grid. The grid size is
approximately the twentieth part of the profile width and height
respectively. [0078] 2) For a fixed angle between height and
y-axis, the largest triangle with centroid C that can be inscribed
in the profile is determined by continuously increasing the side
length of the triangle until the boundary of the profile is
reached. [0079] 3) The largest triangle is calculated for all
centroids on the grid as in 2) and for all angles from 0 to
360.degree. in steps of 0.5.degree. and the centroid which
corresponds to the maximum triangle is determined. Then for all
pixels (x,y) in the surrounding area of this point, the largest
triangle with centroid (x,y) is determined, yielding the maximum
equilateral triangle that can be inscribed. [0080] 4) The area of
the fibre cross section is determined by the colour pixels
identifying the fibre. The area of the optimum equilateral triangle
is determined according to 3). The Delta ratio is now obtained by
dividing the area of the fibre cross section by the area of the
optimum equilateral triangle.
[0081] The procedure is repeated for a total number of 12
individual fibres of the same Sample and the average Delta ratio is
calculated.
Syngina Test:
[0082] The Syngina Test assesses the absorbency of fibres in a
tampon. The test as described below is a simplified version of the
EDANA Test method ERT 350.0-02.
[0083] FIG. 3 shows the apparatus used to perform the test method,
wherein
[0084] 1 denotes the measuring cell
[0085] 2 denotes a supplying vessel
[0086] 3 denotes an overflow line
[0087] 4 denotes a run out
[0088] 5 denotes a condom
[0089] 6,7,11 and 13 denote rubber rings, respectively
[0090] 8 denotes a tampon or tampon-shaped plug
[0091] 9 denotes a tube
[0092] 10 denotes a filling tube
[0093] 12 denotes a run out and
[0094] 14 denotes a mensur.
[0095] A, B denote valves
[0096] The principle of the test method is to simulate the vaginal
environment in the laboratory by applying standard pressure to a
tampon inside a flexible membrane, being formed by a condom.
[0097] By introducing a certain amount of fluid until the tampon
leaks, also the water retention and liquid absorptive capacity and
water displacement can be measured. The tampon weight is taken
before (dry) and after the test (wet) to calculate the weight of
fluid absorbed.
Reagents
[0098] As a Syngina fluid, distilled or de-ionised water is
used.
Preparation of Specimen
[0099] 2.75 g of staple fibre with a humidity of 8-11% are weighed
and fed into a carding machine type USTER MDTA 3, equipped with a
rotoring 3. The speed of the combing roller is 1390 rpm. Each run
takes 75 s. The resulting card sliver, which is about 90 cm long,
is tripled to form a band with a length of 30 cm, which is pressed
between 2 rollers or compacted on a calendar. Application of too
high pressure during compacting of the card sliver may lead to the
formation of a stiff, cardboard-like material, which has to be
avoided.
[0100] The weight of the compacted sliver is adjusted to 2.70 g and
put into a device to form a cylinder by winding. During this
procedure the roll is weighed down by a 150 g counter cylinder.
[0101] The sample is then put into a mechanical press for plugs.
This is a mechanical device, which is able to form tampon-shaped
plugs. The plugs have the same volume, mass and fibre orientation
as a commercial digital tampon, including 8 grooves along the side
of the cylinder. The plug is pressed with 110 Nm for 10 minutes and
is weighed again for redundance immediately before testing.
[0102] In FIGS. 4 to 8, the press by means of which the
tampon-shaped pressed articles for carrying out the Syngina test
are produced is illustrated.
[0103] The press 41 is arranged on a base plate 42 and consists of
a rigidly installed lower bracing 43, in which a lower gripping
device 44 is located, and an upper bracing 45 that is pivotable
horizontally and vertically displaceable by means of a lifting
device 47 and to which an upper gripping device 46 is
connected.
[0104] FIG. 5 shows a section through the upper gripping device 46
according to lines A-A in FIG. 4. The upper gripping device
comprises four upper gripping jaws 461-464.
[0105] FIG. 6 shows a section through the lower gripping device 44
according to lines B-B in FIG. 4. The lower gripping device
comprises four lower gripping jaws 441-444.
[0106] FIG. 7 shows an enlarged section of region Y in FIG. 5. The
exact dimensions of the four upper gripping jaws 461-464 result
from the dimensions in FIG. 7 (in mm). A lower gripping jaw 442 is
illustrated by a segmented line.
[0107] FIG. 8 shows an enlarged section of region Z in FIG. 6. The
exact dimensions of the four lower gripping jaws 441-444 result
from the dimensions in FIG. 8 (in mm). An upper gripping jaw 463 is
illustrated by a segmented line.
[0108] In order to prepare the sample, the previously prepared
compressed and coiled card sliver (weight=2.7 g) is vertically
introduced into the opening between the lower gripping jaws 441-444
and is fixed by the aid of a dynamometric key by applying a slight
pressure on the lower gripping jaws. Subsequently, the upper
gripping device 46 is swivelled in and brought down until the lower
gripping jaws 441-444 and the upper gripping jaws 461-464 are flush
with each other and--such as can be seen in FIGS. 7 and 8--end up
lying alternately adjacent to each other. The coiled card sliver
now is located in the space 48 (see FIGS. 7 and 8) that is
predefined by the gripping jaws 441-444 and 461-464, respectively,
and subsequently is pressed by the tightening of the gripping jaws.
For that purpose, a dynamometric key is put into a square neck (not
shown) provided in the lower bracing 43 and is tightened so
strongly that a torque of 110 Nm is reached. The pressing operation
lasts for 10 minutes. In that way, the pressed article receives its
characteristic shape with 8 grooves.
[0109] This plug can be used for the Syngina test without further
modification. The length of the plug is about 53 mm, its diameter
is 14-15 mm; it does not change its longitudinal or radial
dimension for at least 7 days.
[0110] If a tampon is used as a specimen, the wrapping or the
applicator have to be removed. The test specimen should be
unwrapped immediately before testing, and the withdrawal cord
should be cut away.
[0111] The number of specimens per test should be three.
Condom Installation and Replacement
[0112] A straight unlubricated condom having a tensile strength
between 17 MPa and 30 MPa is used as a test membrane. The condom is
opened and unraveled. The condom is marked at 20 mm and 160 mm
length from the open end.
[0113] The condom is inserted through the chamber 1 of the test
apparatus (FIG. 3) with the aid of a rod, so that the 160 mm mark
rests on the edge of the smaller opening of the chamber 1 (bottom
of chamber 1).
[0114] The tip of the condom is cut and secured with a rubber band
such that the 160 mm mark remains on the edge of the smaller
opening of chamber 1.
[0115] The condom is drawn through the large opening of chamber 1
so that the 20 mm mark rests on the opening's edge and is secured
there with a rubber band.
[0116] Test condoms are replaced (a) if they leak,
(b)--monthly--whichever applies first.
Procedure
[0117] The tampon or the pressed plug prepared according to section
"Preparation of Specimen" above is weighed to the nearest 0.01
gram. The weight is recorded.
[0118] While chamber 1 of the test apparatus is empty, tampon 8 is
placed within the condom 5 as shown in FIG. 3 so that the centre of
the tampon is at the centre of chamber 1 and the bottom end (end
where withdrawal cord is located) is positioned toward the bottom
of chamber 1. It is helpful to use tweezers to place the plug in
the center of this cell.
[0119] After this, valve A is opened so that chamber 1 is filled
with water. A small tube 9 is inserted into the chamber 1, so that
it contacts the top end of tampon/plug 8. Valve A is closed
again.
[0120] Then, valve B is opened for pressure equalisation (a
pressure equivalent to 170 mm water column is established as can be
seen from FIG. 3). Filling tube 10 is inserted with a rubber ring
11. 25 ml test liquid is filled into tube 10. A stop watch is
started.
[0121] After 3 minutes valve B is closed (except there is still
some water replaced via run out 4). If any liquid is standing over
the filling tube 10 and small tube 9, it is sucked off with a
Socorex pipette. Filling tube 10 is removed, and the measuring cell
is raised.
[0122] Tube 9 is removed, valve A is opened and the condom is
relieved, which makes it easy to remove tampon/plug 8 with
tweezers. Afterwards valve A is closed, and chamber 1 is fixed.
[0123] The removed tampon/plug is weighed immediately to the
nearest 0.01 gram. The wet weight is recorded. The remaining water
is drained from chamber 1.
[0124] The test should be repeated three times with a new plug from
the same fibre sample.
[0125] For the test, chamber 1 should be filled without any
bubbles.
Calculation and Expression of Results:
[0126] The absorbency of each specimen tampon/plug is calculated as
follows: A=B-C, wherein
[0127] A=Absorbency of the tampon/plug in grams
[0128] B=Weight in grams of the saturated (wet) tampon/plug
[0129] C=Weight in grams of dry tampon/plug
[0130] The results are expressed to the first decimal. The average
absorbency of the total number of test specimens is calculated.
[0131] The specific Syngina absorbency in g test liquid/g fibre is
calculated by dividing the average absorbency (A) by the average
weight of the dry tampons/plugs (C) in grams.
Water Retention
[0132] Water retention of the fibres is measured according to the
test method described in DIN 53814, using the Wt calculation
scheme.
Water Holding Capacity
[0133] Water holding capacity of the fibres is measured according
to the test method for absorbency of Viscose waddings, Absorbent
described in European Pharmacopoeia 4 01/2002:0034.
6. WORKING EXAMPLES
[0134] Preferred embodiments of the invention are explained in more
detail by way of the following examples.
Example 1
.DELTA.-Shaped Fibre
[0135] A viscose containing 8.70% Cellulose, 5.20% alkali and 2.3%
sulphur having a ripening index of 14.2.degree. Hottenroth and a
viscosity of 58 ball fall seconds (bfs, determined according to
Zellcheming-Merkblatt III/5/E) was spun into a regeneration bath
containing 76.5 g/l sulphuric acid, 272 g/l sodium sulphate and
10.4 g/l zinc sulphate at a temperature of 32.degree. C. by means
of a trilobal spinneret. The spinneret had 625 trilobal holes with
3 limbs of 72.times.33 .mu.m (aspect ratio: 2.18). Before spinning,
5 wt. % of an aqueous solution of polyethylene glycol 1500 were
added to the viscose.
[0136] The spinning speed was 50 m/min. The filaments were
stretched by 55% in a hot secondary bath containing 17 g/l
sulphuric acid, cut into staples of 40 mm length, washed,
desulphurized, bleached, finished at 70.degree. C. and a pH of 5
with 10 g/l of a polyoxyethylene sorbitan fatty acid ester (Tween
20, available from ICI surfactants) and dried.
[0137] The fibres had a titre of 3.0 dtex, a water retention value
of 103% and a water imbibition of 23.8 g/g. The Syngina absorbency
according to the Syngina Test as described above was 6.7 g/g. The
Delta ratio of the fibre was 2.26. Its typical shape is depicted in
FIG. 9.
Comparison Example 2
Spinning without Use of Modifier
[0138] A viscose fibre was spun under the same conditions as
described in example 1 with the exception that no polyethylene
glycol was added to the viscose.
[0139] The fibres had a titre of 2.9 dtex, the water retention
value was 120% and the water imbibition was 24.8 g/g. The Syngina
absorbency according to the Syngina Test as described above was 5.9
g/g.
[0140] The Delta ratio of the fibre was 4.85. Its trilobal shape is
depicted in FIG. 10.
Comparison Example 3
High Sulfuric Acid Content in the Regeneration Bath
[0141] A viscose containing 8.65% Cellulose, 5.16% alkali and 2.3%
sulphur having a ripening index of 14.degree. Hottemoth and a
viscosity of 63 bfs was spun into a regeneration bath containing
131 g/l sulphuric acid, 367 g/l sodium sulphate and 11 g/l zinc
sulphate at a temperature of 49.degree. C. by means of a trilobal
spinneret as described in example 1. Before spinning, 2.5 wt. % of
an aqueous solution of polyethylene glycol 1500 were added to the
viscose.
[0142] The spinning speed was 50 m/min. The filaments were
stretched by 76% in a hot secondary bath containing 19 g/l
sulphuric acid, cut into staples of 40 mm length, washed,
desulphurized, bleached, finished at 70.degree. C. and a pH of 5
with 5 g/l of a polyoxyethylene sorbitan fatty acid ester (Tween
20, available from ICI surfactants) and dried.
[0143] The fibres had a titre of 3.2 dtex, a water retention value
of 87% and a water imbibition of 23.7 g/g. The Syngina absorbency
according to the Syngina Test as described above was 6.6 g/g.
[0144] The Delta ratio of the fibre was 4.07. Its typical shape is
depicted in FIG. 11.
Example 4
.DELTA.-Shaped Fibre
[0145] A viscose containing 8.65% Cellulose, 5.14% alkali and 2.3%
sulphur having a ripening index of 13.60 Hottemoth and a viscosity
of 65 bfs was spun into a regeneration bath containing 85 g/l
sulphuric acid, 276 g/l sodium sulphate and 11 g/l zinc sulphate at
a temperature of 31.degree. C. by means of a trilobal spinneret as
described in example 1. Before spinning, 5 wt. % of an aqueous
solution of polyethylene glycol 1500 were added to the viscose.
[0146] The spinning speed was 50 m/min. The filaments were
stretched by 55% in a hot secondary bath containing 19 g/l
sulphuric acid, cut into staples of 40 mm length, washed,
desulphurized, bleached, finished at 70.degree. C. and a pH of 5
with 10 g/l of a polyoxyethylene sorbitan fatty acid ester (Tween
20, available from ICI surfactants) and dried.
[0147] The fibres had a titre of 2.9 dtex. The Syngina absorbency
according to the Syngina Test as described above was 6.9 g/g.
[0148] The Delta ratio of the fibre was 1.91. Its typical shape is
depicted in FIG. 12.
Example 5
.DELTA.-Fibre, Short-Limbed Trilobal Spinneret
[0149] A viscose containing 8.67% Cellulose, 5.15% alkali and 2.3%
sulphur having a ripening index of 15.degree. Hottenroth and a
viscosity of 62 bfs was spun into a regeneration bath containing 85
g/l sulphuric acid, 277 g/l sodium sulphate and 11 g/l zinc
sulphate at a temperature of 53.degree. C. by means of a trilobal
spinneret. The spinneret had 625 holes, each hole having 3 limbs
with 45.times.33 .mu.m (aspect ratio: 1.36) on an equilateral
triangular core. The radius of the circumscribed circle is 80
.mu.m. Before spinning, 5 wt. % of an aqueous solution of
polyethylene glycol 1500 were added to the viscose.
[0150] The spinning speed was 50 m/min. The filaments were
stretched by 55% in a hot secondary bath containing 17.6 g/l
sulphuric acid, cut into staples of 40 mm length, washed,
desulphurized, bleached, finished at 70.degree. C. and a pH of 5
with 5 g/l of a polyoxyethylene sorbitan fatty acid ester (Tween
20, available from ICI surfactants) and dried.
[0151] The fibres had a titre of 3.2 dtex, a water retention value
of 78.5% and a water imbibition of 18.6 g/g. The Syngina absorbency
according to the Syngina Test as described above was 6.1 g/g.
[0152] The Delta ratio of the fibre was 1.63. Its typical shape is
depicted in FIG. 13.
Example 6
.DELTA.-Fibre Triangular Spinneret
[0153] A viscose containing 8.23% Cellulose, 7.15% alkali and 2.20%
sulphur having a ripening index of 14.5.degree. Hottenroth and a
viscosity of 52 bfs was spun into a regeneration bath containing 98
g/l sulphuric acid, 351 g/l sodium sulphate and 28.2 g/l zinc
sulphate at a temperature of 49.degree. C. by means of a triangular
spinneret. The spinneret had 625 holes, each hole having the shape
of an equilateral triangle with s=129 .mu.m.
[0154] The spinning speed was 55 m/min. The filaments were
stretched by 82% in a hot secondary bath containing 19.6 g/l
sulphuric acid, cut into staples of 40 mm length, washed,
desulphurized, bleached, finished at 70.degree. C. and a pH of 5
with 10 g/l of a polyoxyethylene sorbitan fatty acid ester (Tween
20, available from ICI surfactants) and dried.
[0155] The fibres had a titre of 2.96 dtex. The Syngina absorbency
according to the Syngina Test as described above was 6.4 g/g.
[0156] The Delta ratio of the fibre was 2.03. Its typical shape is
depicted in FIG. 14.
Comparison Example 7
Trilobal Fibre with 89.times.25 .mu.m-Spinneret (Aspect Ratio
3.56)
[0157] A viscose containing 8.80% Cellulose, 5.20% alkali having a
ripening index of 13.5.degree. Hottenroth and a viscosity of 70 bfs
was spun into a regeneration bath containing 76 g/l sulphuric acid,
266 g/l sodium sulphate and 10.4 g/l zinc sulphate at a temperature
of 30.degree. C. by means of a trilobal spinneret. The spinneret
had 625 trilobal holes with 3 limbs of 89.times.25 .mu.m (aspect
ratio: 3.56). Before spinning, 5 wt. % of an aqueous solution of
polyethylene glycol 1500 were added to the viscose.
[0158] The spinning speed was 50 m/min. The filaments were
stretched by 55% in a hot secondary bath containing 17 g/l
sulphuric acid, cut into staples of 40 mm length, washed,
desulphurized, bleached, finished at 70.degree. C. and a pH of 5
with 10 g/l of a polyoxyethylene sorbitan fatty acid ester (Tween
20, available from ICI surfactants) and dried.
[0159] The fibres had a titre of 2.97 dtex, and a water imbibition
value of 25.0 g/g. The Syngina absorbency according to the Syngina
Test as described above was 6.8 g/g.
[0160] The Delta ratio of the fibre was 2.64. Its typical shape is
depicted in FIG. 15.
* * * * *